Asterisk Open-Source PBX System

Use one system to manage voice over IP and conventional phone lines, manage voice mail and run CGI-like applications for phone users.

So, you need to deploy a Private Branch eXchange (PBX) system for your
small office. Or, maybe you want a voice-mail system running on your Linux box
at home. What about an interactive voice response (IVR) system
for home automation? Voice over IP (VoIP) capabilities would be nice too.
How do you do it? One very interesting and powerful solution is
Asterisk, a GPLed PBX system built on Linux that bridges the
gap between traditional telephony, such as your telephone line,
and VoIP. Asterisk also supports a host
of other features that make it an attractive solution. In
this article, I touch on some of these features and
give you enough information to get started without having to
buy any special hardware.

Background

Asterisk is an open-source project
sponsored by Digium. The primary maintainer is Mark
Spencer, but numerous patches have been contributed
from the community. As of this writing, it
runs only on Linux for Intel, although there was some
success in the past with Linux PPC, and an
effort is underway to port Asterisk to *BSD. Digium also
sells various hardware components that operate with
Asterisk (see Resources). These components are PCI cards that
connect standard analog
phone lines to your computer. Other hardware is
supported as well, such as hardware from Dialogic
and Quicknet. Asterisk has its own VoIP protocol,
called IAX, but it also supports SIP and H.323. This
leads us to one of Asterisk's most powerful
features: its ability to connect different
technologies within the same feature-rich
environment.
For example, you could have IAX, SIP,
H.323 and a regular telephone line connecting
through Asterisk (see Figure 1—courtesy of Digium).

The developer can extend Asterisk by working with
the C API or by using AGIs, which are analogous to
CGI scripts. AGIs can be written in any language and are
executed as an external process. They are the
easiest and most flexible way to extend Asterisk's
capabilities (see Listing 1).

If you plan on using a PCI card from Digium,
you should look at zaptel as well. If you
plan on having connectivity, you need
to check out libpri.

There is no configure script, so you simply use make.
You also need readline, OpenSSL and
Linux 2.4.x with the kernel sources
installed in order to compile Asterisk properly:

cd asterisk
make clean install samples

This compiles Asterisk, installs it and also
installs the sample configuration files. The last
target overwrites any existing configuration
files, so either skip this target or back up any
existing configuration files if you want to
preserve them. If you are using zaptel or ISDN,
compile those before compiling Asterisk. Asterisk
is installed in /usr/sbin/ with the configuration
files in /etc/asterisk/ by default. Voice-mail messages
are stored in /var/spool/asterisk/voicemail/.
CDRs for billing and log files are located under
/var/log/asterisk/.

You can start Asterisk by typing asterisk
at the command line. However, the best way to use
Asterisk during the testing phase is to run it with
the -vvvc options. The -vvv option is extra-verbose
output, and the -c option gives you a console
prompt, which allows you to interact
with the Asterisk process. For example, you can
submit commands to Asterisk, such as management
and status commands.

Asterisk's operation and functionality relies on
several configuration files. We discuss three
of them in this article, but several
others exist.
Here, we set up Asterisk so that
users can call each other through IAX. We also
set up voice mail and give users a way to manage
their voice-mail messages.

First at all: The book is only aviable in the german language. The book does describe Asterisk as well as things that are usefull for Asterisk: VoIP-Telefons, Configuration Software, Billing Software, Telefonycards, ...

The book content is sutiable for the german speaking countries: Germany, Austria and Switzerland.

...to the Verizon rj11 jack on the wall!
Or you use the magical wireless connectivity available only in the author's town.

Very technical, very specific article. How about a followup that dumbs it down just a bit, such as, you connect the Digium PCI card to your network, this is how much upload speed you'll need per line, you find a voip carrier by looking for this service (sip...) You can/can't have branch offices with the same number and transfer calls across the city/town with call transfer...

I know someone stuck on Vonage's two line SB plan, who is looking for something cheap, where he can migrate his number to something like Broadvoice or some other service, and have one or two (or more) voice lines, plus a fax line like through Vonage. Number portability takes care of the original number, but the technical details on using Asterisk with a carrier to replace Vonage (or Broadvoice which has their own adapters like Vonage, or bring your own adapter) still isn't clear.

What exactly needs to be done to migrate from Vonage Voip to Asterisk, where I can get one voice and one fax (or actually 2 voice lines) which actually has functional call "hunting" for each voice line? Who do I call to order the service, once I have a dedicated box for Asterisk and Digium modems? Unless the cost comes in less than either Vonage for two lines, or Broadvoice or other Voip for multiple single lines, what's the point besides the geek factor? Using call forwarding on busy with multiple single lines, you get all the benefits of all the other services, without worrying about another point of failure in the hardware, a huge UPS for a computer vs. a UPS for a few phone adapters, plus the cost of electricity of running that computer 24/7 every month.

While the technical details are nice, the major part of the story, the connection explanation/possibilities as compared to something like Vonage/Broadvoice so one can fully understand what/why is missing. The technical details would be a nice addition, but I doubt that most post-purchase users are going to use this article for relying on their phone system when the mailing list for Asterisk and the abundant docs online are all available and will be utilized anyway.

Good technical explanation, but the article misses the mark. Thanks for the article anyway.

Xorcom has released version 0.9 of Debian and Asterisk auto-installer. It can turn any PC to pre-configured PBX from scratch in a few minutes, and contains lots of extra software and features. It is free and open source.Asterisk auto-install CD